[Voyage-linux] Re: PPS kernel patches

Thu Dec 27 14:42:11 HKT 2007

I have been using Garmin GPS25 and GPS18 gps receivers, both of which
have rs232 compatible outputs. They also have a hard wired 1pps port
that I connected to the DCD pin (pin 1 on a 9 pin) of the connector.
Yes, I did need to do some soldering.

These work well on the big bells an whistles linux distros, but my
goal is an appliance that "just works" when you turn it on. The work
on Voyage is greatly appreciated by me because it is perfect for this
goal.

I haven't followed the kernel very closely to see if the pps patch has
been added to the source tree. But the links you show are for the
kernel. ntpd has the interface already built-in to accept pps and
serial data - you won't need to patch it.

Thanks!

Clark
kr6au

On Dec 26, 2007 5:34 PM, Kim-man 'Punky' TSE <punkytse at punknix.com> wrote:
> Mark and Clark,
>
> Don't get me wrong, but I spend a few minutes on the links below and I
> found that it is indeed for 2.0/2.2/2.4 kernel!?
>
> Luckily I find this one.
>     http://wiki.enneenne.com/index.php/LinuxPPS_support
> and patches here:
>     http://ftp.enneenne.com/pub/misc/linuxpps/patches/
>
> Including patch is OK, but patching ntpd may be a issue ... (for me).
>
> Instead, you need special equipment for getting PPS signal, at least you
> need soldering things.  What GPS device you usually uses for 1PPS?
>
> Regards,
> Punky
>
> Mark Phillips wrote:
> > You need to look at the NTP sources. These contain a kernel patch. If I
> > understand it correctly, GPSD and others pick up the 1PPS via the kernel
> > (usually connected to the DCD pin on the serial port).
> >
> > They are available here ftp://ftp.kernel.org/pub/linux/daemons/ntp/PPS/
> > and a rough howto is available here http://etienne.favey.ch/ntp/
> >
> > Thanks very much for looking at this!
> >
> > Mark
> >
> > On Mon, 2007-12-24 at 09:27 +0800, Kim-man 'Punky' TSE wrote:
> >
> >> Hi ,
> >>
> >> But where can I get the 1PPS patch for Linux and instruction?  As far as
> >> I read gpsd documentation, it indeed support 1PPS as long as you have
> >> the proper equipment.
> >>
> >> What is the different between gpsd support for 1PPS and the 1PPS patch
> >> for the time server?
> >>
> >> Regards,
> >> Punky
> >>
> >> Mark Phillips wrote:
> >>
> >>> Any thoughts/comments on this Punky?
> >>>
> >>>
> >>>
> >>> On Mon, 2007-12-10 at 14:33 -0500, Mark Phillips wrote:
> >>>
> >>>
> >>>> I have mine setup in a similar way but it is not a true time server in
> >>>> that because of the lack of a disciplining kick on a regular basis it is
> >>>> able to drift between time updates.
> >>>>
> >>>> The problem with NMEA time strings is that they tend to come in a
> >>>> cluster and not at all every second or 3 seconds or 5 seconds. They come
> >>>> along whenever the GPS processor has time to spit them out.
> >>>>
> >>>> The 1PPS pulse from the GPS system is not derived from the decoded data
> >>>> but rather is an inherant component of the GPS signal along with the
> >>>> 10KHz pulse and thus is more reliable.
> >>>>
> >>>> I'd still like to see a 1PPS patched kernel particularly as it would
> >>>> then allow for connections to things like Frequency Standards and LORAN
> >>>> RX's etc. Heck, one could even connect it up to the mains after a very
> >>>> simple signal divider (trick used on clock radios etc) is added.
> >>>>
> >>>> Mark
> >>>>
> >>>> On Thu, 2007-12-06 at 19:24 +0800, Kim-man 'Punky' TSE wrote:
> >>>>
> >>>>
> >>>>> Hi guys,
> >>>>>
> >>>>> Forget to mention, I have setup voyage attached to Garmin GPS18/USB and
> >>>>> get NTP time sync'd.  Of course, this device is not PPS-capable, but it
> >>>>> works without any patch to the kernel and NTP daemon.   See my blog article:
> >>>>>
> >>>>>     http://www.punknix.com/?q=node/116
> >>>>>
> >>>>> Regards,
> >>>>> Punky
> >>>>>
> >>>>> Mark Phillips wrote:
> >>>>>
> >>>>>
> >>>>>> Now I think about it, updating the gpsd package would also be useful for
> >>>>>> this purpose.
> >>>>>>
> >>>>>> FYI, my NTP server is running Voyage on a Neoware N3000 thin client
> >>>>>> (ebay $20). It has a 300MHz via processor in it as well as an IDE
> >>>>>> interface which is now running a CF card. The GPS RX plugs into ttyS0
> >>>>>> and I'm running gpspipe on ttyS1 to allow my Nixie tube clock to correct
> >>>>>> itself.
> >>>>>>
> >>>>>> Mark
> >>>>>>
> >>>>>> On Fri, 2007-11-30 at 05:10 +0000, Clark wrote:
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>> Mark Phillips <g7ltt at ...> writes:
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>> Hi all,
> >>>>>>>>
> >>>>>>>> Is there anywhere that I can register a feature request for adding PPS
> >>>>>>>> to the kernel for use in NTP apps? This would be really handy I think.
> >>>>>>>>
> >>>>>>>> Thanks
> >>>>>>>>
> >>>>>>>> Mark
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>> I would really like that too!
> >>>>>>>
> >>>>>>> I have been using Voyage to try to create an NTP appliance  'cause the
> >>>>>>> commercial ones are WAY beyond my budget!
> >>>>>>>
> >>>>>>> I appreciate the work on Voyage so far!
> >>>>>>>
> >>>>>>> Thanks!
> >>>>>>>
> >>>>>>>
> >>>>>>> _______________________________________________
> >>>>>>> Voyage-linux mailing list
> >>>>>>> Voyage-linux at list.voyage.hk
> >>>>>>> http://list.voyage.hk/mailman/listinfo/voyage-linux
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>
> >>>>>
> >>
>
>
> --
> Regards,
> Punky
>
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